Multilayer emulsions as delivery systems for controlled release of volatile compounds using pH and salt triggers

Multilayer oil-in-water (M-O/W) emulsions were compared to primary oil-in-water (P-O/W) emulsions as carriers for volatile organic compounds (VOCs) under various environmental conditions (pH and salt). The M-O/W emulsion consisted of soy oil coated with β-lactoglobulin (βLG) and pectin layers. The release of VOCs with different physiochemical properties from aqueous solutions and emulsion systems was measured using static and dynamic headspace methods. The partition coefficients (K) calculated by the phase ratio variation (PRV) method, showed different volatile release profiles between the emulsion types. An increase in VOC release was found for the unstable P-O/W emulsion at pH 5, whereas M-O/W emulsions were stable at the same pH and retained the hydrophobic VOCs. Hydrophobic interactions and hydrogen bonds with the secondary dense layer of pectin may be responsible for the improved retention. Increasing pH and ionic strength acts as a VOC release trigger to detach the pectin from the interface. The release rates from initial dynamic curves support the results under equilibrium conditions. The results of this study demonstrate the capability of using M-O/W emulsions for controlled release of VOCs, as well as an alternative system to create stable emulsions with similar VOC release profiles.     

Functionalised iron nanoparticle–penicillin G conjugates: a novel strategy to combat the rapid emergence of β-lactamase resistance among infectious micro-organism

The emergence of novel mechanisms of β-lactam resistance and their gain by infectious micro-organisms are posing a huge clinical threat to human health. It creates a need to generate novel resistant antibiotic molecules to counter their attack. In the present study, a novel strategy is developed to synthesise β-lactamase-resistant penicillin G molecules by using the unique properties of iron nanoparticles. Spherical monodispersed iron nanoparticles were prepared by a simple chemical reduction method. The formation process of the iron nanoparticles was investigated by ultraviolet–visible spectroscopy and atomic force microscopy. Free amine groups introduced on the surface of native iron nanoparticles by coating a uniform layer of polyaniline were confirmed by Fourier transform infrared spectroscopy and scanning electron microscopy. Functionalised iron nanoparticles were then grafted to the C3 carboxyl group of the β-lactam ring of penicillin G in the presence of N-(3-dimethylaminopropyl)-N′-ethylcarbodiimide hydrochloride with a conjugation yield of 187.7 μg mg^?1. These novel iron nanoparticle–penicillin G conjugates showed a very good growth inhibition against β-lactam-resistant Staphylococcus aureus. This work thus describes a novel strategy for synthesis of nanoconjugates which can be used to design novel bactericidal materials against β-lactam-resistant infectious micro-organisms.     

Kinetic analysis of bile salt passage across a dialysis membrane in the presence of cereal soluble dietary fibre polymers

The kinetics of passage of a model bile salt and complete porcine bile across a dialysis membrane, in the presence and absence of two cereal-derived soluble dietary fibre polysaccharides, were studied as a model for passage across the unstirred water layer that lines the small intestine. A first-order kinetic analysis allowed rate coefficients to be derived which quantified the effectiveness of barley mixed linkage β-glucan and wheat arabinoxylan in retarding the transport of bile. For both, a model bile salt and complete porcine bile, rate coefficients decreased with both concentration and viscosity. A combination of viscosity and molecular interaction effects is suggested to control the effect of the two polysaccharides on the transport of bile.     

In vitro release profiles of β-carotene encapsulated in PHBV by means of supercritical carbon dioxide micronization technique

The main objective of this work was to investigate the characteristics of the in vitro release of β-carotene encapsulated in poly(hydroxybutyrate-co-hydroxyvalerate) (PHBV) using the solution enhanced dispersion by supercritical fluids (SEDS) technique. The release tests were performed using encapsulated complex with solute loading from 2.24 to 27.5% and encapsulation efficiency from 7.75 to 55.54%. The release profile assays were performed in ethyl acetate, n-hexane and anhydrous ethanol, and monitored by UV-vis spectrophotometer concentration analysis. Results indicated higher initial release rates in ethyl acetate and in n-hexane, with cumulative release percentage varying from 31.50 to 69.58% and from 42.08 to 55.96%, respectively. For anhydrous ethanol the maximum concentration was reached at 180 min, 300 min and 10 days, depending on the initial amount of β-carotene, with cumulative release ranging from 45.27 to 88.22%. In general, the β-carotene release can be controlled by the organic solvent used and by the initial amount of solute encapsulated, aspects that help the selection of the conditions to achieve the desired release profiles for a specific application.     

Evaluation of hydroxyapatite and β-tri calcium phosphate microplasma spray coated pin intra-medullary for bone repair in a rabbit model

Here we report a comparative study of the healing kinetics of surgically created artificial defects in the tibia of New Zealand white rabbits. Comparison of the healing kinetics was made for uncoated conventional SS316L intramedullary pins, and the same pins with microplasma sprayed (MIPS) pure hydroxyapatite (HAp) and beta-tri calcium phosphate (β-TCP) coatings. After thorough material characterizations including XRD, FTIR, SEM, etc., MIPS coated pins were implanted to such animals. Serum biochemistry, radiology and fluorochrome labelling were used to evaluate the comparative healing kinetics of these implants in vivo. In comparison to those of the uncoated pins, the pins coated with both MIPS HAp and β-TCP showed significant increment of alkaline phosphatase up to 15th postoperative day, insignificant changes in serum phosphorus and calcium with uneventful healing of bone defect. There was development of Havarsian canals and well-defined peripherally placed osteoblasts along with evidence of angiogenesis and comparatively more new bone formation in the defect site. On a comparative scale, the performance of the β-TCP coated intramedullary pins was much better than that of the pure HAp coated pins than the uncoated intramedullary pins.     

黄芪甲苷对镉致大鼠支持细胞损伤的保护作用

目的：探讨镉对原代培养大鼠睾丸支持细胞的毒性机制及黄芪甲苷的保护效果。方法：空白对照组、0.5%二甲基亚砜（DMSO）组、镉（50μmol/L）组、镉（50μmol/L）加黄芪甲苷（分别为5、10、20mg/L）组的培养支持细胞用于四甲基偶氮唑盐（MTT）细胞活性实验,DMSO组比较用于验证0.5%DMS0溶剂是否对细...     

A kinetic study of electrochemical lithium insertion in nanosized rutile β-MnO2 by impedance spectroscopy

The kinetics of the electrochemical lithium insertion reaction in nano-sized rutile β-MnO₂ has been investigated using ac impedance spectroscopy. The experimental kinetic data are obtained for a rutile compound synthesized by ball-milling the powder produced from the heat treatment of manganese nitrate salts. The results are discussed as a function of the Li content for 0 < x < 0.6 and the number of cycles in the 4.1–2 V window. From a comparison with data obtained on the micro-sized oxide, an improved kinetics is found with D_Li values for the apparent chemical diffusion coefficient of lithium much higher by one order of magnitude than in microsized oxide. Impedance behaviour of the ball-milled rutile β-MnO₂vs cycles demonstrates a new system takes place from the second cycle, characterized by a significant improvement of Li diffusion by a factor 5 and a cathode impedance which decreases by a factor 2, remaining thereafter unchanged during cycling.     

Chitosan—A versatile semi-synthetic polymer in biomedical applications

This review outlines the new developments on chitosan-based bioapplications. Over the last decade, functional biomaterials research has developed new drug delivery systems and improved scaffolds for regenerative medicine that is currently one of the most rapidly growing fields in the life sciences. The aim is to restore or replace damaged body parts or lost organs by transplanting supportive scaffolds with appropriate cells that in combination with biomolecules generate new tissue. This is a highly interdisciplinary field that encompasses polymer synthesis and modification, cell culturing, gene therapy, stem cell research, therapeutic cloning and tissue engineering. In this regard, chitosan, as a biopolymer derived macromolecular compound, has a major involvement. Chitosan is a polyelectrolyte with reactive functional groups, gel-forming capability, high adsorption capacity and biodegradability. In addition, it is innately biocompatible and non-toxic to living tissues as well as having antibacterial, antifungal and antitumor activity. These features highlight the suitability and extensive applications that chitosan has in medicine. Micro/nanoparticles and hydrogels are widely used in the design of chitosan-based therapeuticsystems. The chemical structure and relevant biological properties of chitosan for regenerative medicine have been summarized as well as the methods for the preparation of controlled drug release devices and their applications.     

Facile synthesis and catalytic properties of single crystalline β-MnO2 nanorods

Single-crystalline β-MnO₂ nanorods were successfully synthesized through facile reflux treatment of KMnO₄ and MnSO₄ in HNO₃ solution. TEM and SEM images show that the synthesized β-MnO₂ nanorods exhibited diameters of 20–50 nm, and lengths that ranged from approximately 0.5 to 2.0 μm with decreasing HNO₃ concentrations from 0.8 to 0.1 mol/L. The β-MnO₂ nanorods underwent three primary evolutionary stages over time. They exhibited excellent catalytic properties for the degradation of methylene blue (MB) by a Fenton-like reaction.     

Ⅰ型新德里金属β内酰胺酶的生物信息学分析

目的应用生物信息学方法分析Ⅰ型新德里金属β内酰胺酶(New Delhi metallo-β-lactamase 1,NDM1)的基本性质,并与常见的β内酰胺类抗生素进行分子对接,在理论上研究NDM1对β内酰胺类抗生素和抑制剂的水解活性。方法应用EMBOSS 6.3.1.1软件包的程序分析NDM1的基本性质,并分别利用SWISS-MODEL同源建模和PHYRE 2.0折叠识别法构建NDM1的空间结构,再运用Arguslab 4.0软件的dock模块进行β内酰胺类抗生素与NDM1分子对接。结果 NDM1共270个氨基酸残基,理论等电点为6.3,包含1个跨膜区,α螺旋占27%,β折叠占34.5%;与抗生素对接能量由低到高依次为氨苄西林、头孢拉啶、阿莫西林、头孢唑林、甲氧西林、美罗培南、亚胺培南、氨曲南、克拉维酸。结论NDM1对氨苄西林催化效率最高,对氨曲南催化效率最低,克拉维酸对NDM1无抑制作用。